Aluminum TIG AC vs DC w/Argon

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This is a comparison of TIG AC versus DCEN, on 1/16" aluminum.60 amps, 10 cfh argon with gas lens, 3/32" 2% thoriated sharp, arc gap approx. 1/16", torch angle approx. 10 deg. push, travel speed approx. 6 ipm.  Lincoln Invertec 205, AC balance 85%, AC frequency 150 Hz.Bead on plate, no filler added.  Cleaned front and back with SS wire brush by hand.  Type of Aluminum unknown.Front side, DCEN on top.http://i56.photobucket.com/albums/g1...p/DSCN1168.jpgBack side, DCEN on top, no penetration on AC.http://i56.photobucket.com/albums/g1...p/DSCN1169.jpgDCEN TIG with argon on thin aluminum, not bad, just need clean base metal.
Reply:Nice stuff Pulser.  Thank you DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:Looks just like it should, and proof that AL can be and is welded with dc. You just have to work fast when using dc to avoid the way AL oxidizes, and like you said make sure it's really clean.The difference between art and craft is the quality of the workmanship. I am an artist.
Reply:Demonstrates the differences in heat input well but an autogenous bead on a piece of plate doesn't compare to a real world joint.
Reply:very nice stuff pulser... thanks. was that done with one of your spiffy little CNC machines?Later,Andy
Reply:Andy,thanks.  No CNC, just me trying to be steady like a machine.  I think I maintained the arc gap, the travel speed was the most difficult to try to make the same for both welds.  That's what I love about a machine, everything is so repeatable, you can compare welds at different amperage, travel, gap, whatever, and be confident that you are only seeing the effect of that one variable.
Reply:Pulser, thank you very much for drawing this thread to my attention.I LOVE the look of that DC weld bead, although it looks like there is quite a bit of penetration.Any chance we can see a few different joints welded (and maybe fused?) using the DC/Argon process on 16 or 14 gauge Aluminum sheet?I'm new to welding so I'm not sure what all the joint types are called, but a "T" joint and what you'd see on the outside corners of a box made from sheet metal would be great if you're taking requests
Reply:It works real well on real world joints hotrodder. I used to use dcen w/helium (I prefer argon but my boss would only buy helium) on 1/2" regularly. We were having problems with the welds cracking out over time using ac. I tried the dc and it cured the problem and went a whole lot faster.The difference between art and craft is the quality of the workmanship. I am an artist.
Reply:OK, I tried it.  I had these "cupons" of unknown make up.  I wire wheeled them and spaced them out a little.  I used pure argon, DCEN.  It was quiet for welding aluminum.  You can see from the beads it took me a while to learn KEEP THE ROD IN THE PUDDLE.  The oxidation gets in the way.  Amps I don't know.  I set it on 185 and used the foot pedal.  Getting towards the end, I had to back off a lot.Back sideReal world weldin.  When I grow up I want to be a tig weldor.
Reply:Then I flipped it over and ran a bead over he back side. After wire brushing the heck out of it with a SS brush.I picked the best spot and cut it with a hacksaw.I can see how it would work, when things are going right, It moves right along.  It gives new meaning to "watch the puddle".David Last edited by David R; 07-30-2008 at 08:41 PM.Real world weldin.  When I grow up I want to be a tig weldor.
Reply:It works better with helium....and doesn't turn out so dirty looking.
Reply:I can see how it would work, but thin plate would be a b*tch.  I have AC and a spoolgun, so I doubt I will use it in the real world.  Was fun trying.David Real world weldin.  When I grow up I want to be a tig weldor.
Reply:On this Aluminum, Argon and DCRP can be used if the tungsten is BIG and the material is thin. The cleaning action is very good.I have welded 1/4" thick aluminum electrical enclosures in the field using GTAW DCSP and Helium. Havent tried Argon. The finished welds look like any others except for the black smoke. The puddle can be a little un-cooperative at times if the lleast amount of trash is in the joint.Repaired a friends pontoon boat last year with a thunderbolt 225 AC/DC and a bottle of helium.Have a nice dayhttp://www.weldingdata.com/
Reply:David,interesting experiment, thanks for sharing.  In the interest of "science", not to critisize your work, I think the DCEN Argon aluminum thing needs some more discussion.  It seems like something went wrong with those welds, not related to DCEN or argon, that is pretty bad oxide contamination.  DCEN and helium works well, we know that, so there is no reason that argon should not also work well, just not as much heat transfer for a given amperage.   I think that if the shielding is sufficient, and the oxide on the base metal is removed, you will get welds much "cleaner" than what happened with these welds.Just for the sake of discussion, assume you look at the most extreme "clean" conditions, you put the aluminum plate in an inert glovebox with oxygen and moisture levels below 10 ppm.  You remove the surface oxide by brushing it inside the box, so new oxide does not form, because there is no oxygen.  You weld in the inert atmosphere and the weld is pristine, no oxidation.Now look at the real world again, cleaning and welding out on the work bench.  You do the best you can to remove the oxide and provide the best shielding, and I think it is possible to get better results than what you got.One thing that may have hurt you is the power wire wheel.  This can be too aggressive, actually causing increased oxidation due to friction heating in air.  Then, the other thing is shielding, did you use a big ole gas lens?I'll see if I can try some welds, heavier aluminum with filler wire, DCEN and argon.  I'm sure it's not as easy as I think it should be.
Reply:David,I may have misunderstood. Did you weld the aluminum with helium in DC mode with your lincoln?ThanksLONGEVITYPhone: 877-566-4462
Reply:David,I tried some DCEN argon with filler on aluminum today, pictures to follow later, and it is very difficult to get everything oxide free enough to make a smooth weld.  I had pretty good luck with some thin sheet, it looked like the sheet oxide was not too bad, but I could actually see the oxide from the wire being deposited into the puddle with ever dip, and I was careful not to pull back too far out of the shield.  Each dip of filler left a crusty dark patch of oxide on the weld surface.  I guess a person could figure out the right kind of "sand" paper to use on the wire, probably not alumina oxide, then acetone wipe, right before making the weld.  Anyway, with really tedious cleaning/oxide removal, the DCEN with argon is possible, but AC wets out and flows so much better it is the way to go on thin aluminum.
Reply:I would suggest clean unused steel wool followed by a wipe with a clean cloth. Still not as nice as AC, but it may help. I have used DCRP to clean surfaces difficult to reach.While repairing a piece of cast aluminum that I had preheated and was starting to clean using DCRP, it puddled up nicely and I made the weld on DCRP with Argon. It was a boat prop tip and welded up nicely. I may have had 75/25 Ar/He.Have a nice dayhttp://www.weldingdata.com/
Reply:Originally Posted by pulserDavid,  It seems like something went wrong with those welds, not related to DCEN or argon, that is pretty bad oxide contamination..............Just for the sake of discussion, assume you look at the most extreme "clean" conditions, you put the aluminum plate in an inert glovebox with oxygen and moisture levels below 10 ppm.  You remove the surface oxide by brushing it inside the box, so new oxide does not form, because there is no oxygen.  You weld in the inert atmosphere and the weld is pristine, no oxidation.Now look at the real world again, cleaning and welding out on the work bench.  You do the best you can to remove the oxide and provide the best shielding, and I think it is possible to get better results than what you got.One thing that may have hurt you is the power wire wheel.  This can be too aggressive, actually causing increased oxidation due to friction heating in air.
Reply:Jolly Roger, I know DCEN works well, the point i was making is that running an arc over a piece of metal does not compare to a real joint- no disrespect to Pulser but anyone capable of holding a torch could achieve thatI haven't used DCEN and He on Al for a good few years, never did a lot anyway but we only switched to DCEN above 6mmGave it a little go today with argon on some 1mm sheet. Oxide was removed from the base with a SS brush, edges scrapped too. Filler was cleaned with scotchbrite, both were then solvent wiped until the cloth remained clean- took around twice as long as it would to clean off the etched zone after welding with AC , obviously the welding itself was fasterI haven't bothered with pics as although i got a full pen weld they were very ugly and dirty never any sign of a puddle (had to use 'the force' ). I won't be bothering again
Reply:Like I said, I can see how it would work, just not in my world.Its nice to see more trying it.David Real world weldin.  When I grow up I want to be a tig weldor.
Reply:Originally Posted by gaustinI would suggest clean unused steel wool followed by a wipe with a clean cloth.
Reply:Originally Posted by EngloidSTEEL wool can make aluminum rust.
Reply:Originally Posted by gaustinI would have to disagree but only based on my limited experience and the fact that steel is harder than aluminum. Clean, new steel wool is pretty much free of any loose particles.
Reply:When you guys wire alu with a spool gun, do you use AC or DC + or - ? I always use DC + with argon.
Reply:Originally Posted by EngloidJust how large a particle do you think it takes to create rust?  It doesn't have to become embedded into the aluminum.  Remember that EVERYTHING is magnetic to some degree.  Even water molecules stick to each other.Picks of 1/16" aluminum TIG with DCEN, Argon, and 1/16" 5356 filler.1/8" 2% thoriated sharp tungsten, Argon at 20 cfh throung gas lens and #8 cup (1/2" dia.) Lincoln Invertec inverter starting amps 60, reduced to unknown amperage during weld via foot pedal.Frontside top weld is a butt joint, bottom weld is bean on plate.  I could see crusty dark oxide deposits coming from the filler metal.http://i56.photobucket.com/albums/g1...p/DSCN1296.jpgBackside top weld shows that butt joint did not want to wet together due to oxide, thus leaving a line.  Bottom weld without joint shows no line.http://i56.photobucket.com/albums/g1...p/DSCN1305.jpgLooks like super cleaning (oxide removal) is required for both base metal and filler metal.
Reply:Nice stuff, thanks"Buttcheeks"  I can't see how you could avoid them, there isn't even any cleaning on top.  That is why I welded both sides of the one I tried.It seems to take a lot less heat than on AC.David Real world weldin.  When I grow up I want to be a tig weldor.
Reply:I got full pen without any suckback, for about an inch . Even uglier than those posted though
Reply:So, is the bottom-line "Use AC for aluminum" still valid?Roger
Reply:DCSP Works fine. I left a manufacturer yesterday that used DCSP and Helium for parts used in the aerospace industry. DCSO with ARgon is tough but can happen. DCRP can be done with Argon.I got to see some friction stir welds . Never got to see that before in person.Have a nice dayhttp://www.weldingdata.com/
Reply:Originally Posted by RogerRogerSo, is the bottom-line "Use AC for aluminum" still valid?Roger
Reply:Im really lost here, so its possible to weld aluminum with DCEN we just now made that clear. But looking at your beads I thought I was looking at the back side of the weld. Was this without filler? I'd like to see a DCEN aluminum weld with filler if thats the case. I really like that you are thinking out of the box though .
Reply:Originally Posted by SR20steveIm really lost here, so its possible to weld aluminum with DCEN we just now made that clear. But looking at your beads I thought I was looking at the back side of the weld. Was this without filler? I'd like to see a DCEN aluminum weld with filler if thats the case. I really like that you are thinking out of the box though .
Reply:Originally Posted by SR20steveIm really lost here, so its possible to weld aluminum with DCEN we just now made that clear. But looking at your beads I thought I was looking at the back side of the weld. Was this without filler? I'd like to see a DCEN aluminum weld with filler if thats the case. I really like that you are thinking out of the box though .
Reply:3/32 red thoriated sharp point 145ish amps 1/16 4043 filler and argon at about 18 cfh 1/8 inch aluminum with a  fillet weld Attached ImagesMiller Xmt 350Lincoln Ln-25Ahp 200xSmith Gas Mixer AR/HTig is my Kung FuThrowing down dimes and weaving aboutInstagram http://instagram.com/[email protected]
Reply:Originally Posted by WeldingWookie3/32 red thoriated sharp point 145ish amps 1/16 4043 filler and argon at about 18 cfh 1/8 inch aluminum with a  fillet weld
Reply:Originally Posted by geezerI am assuming you done these good looking welds with a transformer machine, correct? If so, was it the Precision 275?  Thanks
Reply:Originally Posted by Ag SpecialtiesWhen you guys wire alu with a spool gun, do you use AC or DC + or - ? I always use DC + with argon.